The microstructures of Au plate crystals electrodeposited on Fe substrate from hydrochloric auric chloride baths were examined by electron diffraction and observation under an transmission electron microscope.
The results obtained were as follows
(1) Rotation moiré patterns were observed in the Au plate crystals, which showed that some of the crystals grew in an orientation at a certain angle to the main plate crystals in their growing process. The angle of rotation was 1-4°and the rotation process of crystals was in three dimensions,
(2) The number of the rotation moiré patterns was larger in the Au film prepared from a bath of lower pH than that from a bath of higher pH; in addition, the patterns were more remarkable in a film of high indices than that of low indices.
(3) The nucleation sites of new crystals, forming the rotation moiré patterns with Au plate crystals in the electron micrograph, showed strained fields such as sub-grain boundaries and dislocations in the Au plate crystals. The rotation of the crystals in their growing process contributed to the relaxation of strains in the Au film.
(4) The dislocation density in the Au plate crystals electrodeposited from the bath of pH<<0.3 (far less than 0.3) was about 1×10¹¹cm/cm³.
(5) Hydrochloric acid added to the auric chloride bath had little effects on the width and length of the twin, which had been introduced for the relaxation of strains in the Au film.

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The values of analysis of sulfuric acid in chromium plating baths, especially in a high concentrated bath containing fluosilicic acid, were given with the results of higher than true values. The measuring process was by centrifugal precipitation method as follows: the precipitate of barium sulfate, which had been obtained by precipitating sulfuric acid with barium chloride, was settled in a measuring tube by a centrifugal separator and the volume of deposits was measured.
It was found that these higher values of analysis were due to the deposition of precipitates of barium chromate and barium hexafluosilicate together with barium sulfate; and the values depended on the contents of chromium (VI) oxide and potassium hexafluosilicate as well as that of sulfuric acid in the plating bath. Therefore, the values of analysis of sulfuric acid by centrifugal precipitation method was apparently observed with higher results by the higher contents of deposits other than barium sulfate.
It was further found that the total volume of these mixed precipitates also depended on the chemical conditions of the bath, besides the contents of constituents; and considerably slight errors of values were observed when the bath reached a chemically stable state.

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Experiments were conducted to find the optimum bath composition and plating condition for obtaining a bright chromium plating from CrO₃ baths of concentrations lower than 50g/l.
The following results were obtained:
(1) The optimum bath composition for bright chromium plating was CrO₃/H₂SO₄/Na₂SiF₆=100/1/1 and the concentration of CrO₃ was 25-50g/l.
(2) The plating conditions seemed to be almost the same as those of the normal bath of 250g/l CrO₃. However, the range for brightness was narrower with the decrease in CrO₃ concentration of the bath.
(3) Chromate films appeared on the surface of the chromium plating from CrO₃ baths of low concentrations. The films could be removed by dipping for a short period in the plating bath after deposition.

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The bath voltages of chromium plating were studied at various concentrations of CrO₃ and under various plating conditions.
The following results were obtained:
(1) A higher bath voltage was required for a CrO₃ bath of lower concentration. When the voltage of CrO₃ 250g/l bath was taken as the standard, the voltage required was about 2 times for 50g/l bath, about 4 times for 25g/l bath, and about 6 times for 12.5g/l bath at 1l beaker test.
(2) Assuming that the hypothetical value of resistance voltage of chromium plating bath calculated from its conductivity is E_ohm and the real value is E'_ohm, the following relation was derived:
k=E_ohm/E'_ohm=K/K'=(2.4±0.2)l1/3
where K and K': Hypothetical and real cell constants, respectively
l: Distance between electrodes
(3) Accordingly, k was called cell constant ratio.

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The covering powers of chromium platings from both of the plating baths of low and high concentrations were studied.
The following results were obtained:
(1) The covering power by the Hull Cell Test was much higher in the bath of low concentration than in that of high concentration.
(2) On the contrary, the covering power by the parallel or bend cathode process was lower in the bath of low concentration than in that of high concentration.
(3) The above two contradictory phenomena were due to the fact that the current was likely to be concentrated along the edges of the specimen so that the current density in the center was lowered; and the lowering degree of the current density was greater in the bath of low concentration than in that of high concentration.

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The electroless plated ductile nickel layer was not obtained from the known electroless nickel plating baths generally used; but, it was obtained from the bath containing sodium acetate and sodium hypo-phosphite as a reducing agent at a slow deposition rate.
Among these baths, the conposition of 10g/l of nickel chloride, 5g/l of sodium hypo-phosphite, and 75g/l of sodium acetate gave a deposited layer of good appearance at a moderate deposition rate in practice.
It was found that the above bath was able to control the crack formation caused by bending of the electroless plated nickel layers, when the bath was adjusted with nitric acid to pH of about 5 and cobalt sulfate and saccharin as stress-relieving agents were further added to it. The bath temperature preferable was 80°C or higher.

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The laminates of polyvinyl chloride to metals have widely been applied to exterior building materials in recent years.
These materials usually must have durability for a long period with out repair, re-painting, etc. Accordingly, the weather-resistance of surface polymer such as polyvinyl chloride may be a very important property.
This paper describes the factors which gave effects on photodegradation of polyvinyl chloride on various base metals.
The results revealed that the effects of ultraviolet ray reflection of various metals on the photodegradation were not so remarkable. However, it was observed under accelerated photodegrading condition by using a weather-meter that the photodegradation was affected by other factors such as electrochemical corrosions of base metals, different thermal conductivities of metals, etc.
As the results of electrochemical corrosions, the metal ions migrated into the polyvinyl chloride layer, which was led to powerful photodegradation by such ions having catalytic activity.
Therefore, it was concluded that the effects of base metals on photodegradation of polyvinyl chloride would be explained by the catalytic action due to electrochemical corrosions rather than ultraviolet reflection ratios of base metals.

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